Transcript Unraveling a Fish Myth

Unraveling a Fish Myth
Unraveling a Fish Myth
• Pervasive rhetoric: …aquaculture is less
efficient than traditional fishing…
• “It takes 2-5 lbs of wild fish to produce 1 lb of
farmed fish. If you do the math, this isn’t
sustainable.”
• Dir. Center for Coastal and Watershed Systems, Yale
University
• Back to basic biology
Unraveling a Fish Myth
• TE in Nature
– Avg. trophic efficiency = 10%
– 10lbs (L#N)  1lb (l#N+1)
– Fish Prod = Prim Prod x (TE)↑exp TL
0.9
large tuna, sharks, billfish (0.7)
4.65
6.21
small tuna, salmon, squid (4.65)
31
31
chaetognaths, micronekton (31)
mesopelagic vertical migrators (63)
157
470
313
crustacean zooplankton (470)
DOC (32,776)
2,351
2,351
ciliates (2,351)
11,754
11,754
flagellates (11,754)
bacteria (16,388)
42,380
18,163
algal picoplankton and
nanoplankton (60,543)
invertebrate carnivores
(1.4)
natural mortality and fishing
pelagic fish (9.3)
6.8
2.3
crustacean zooplankton (9.1)
ciliates (2.6)
42.75
flagellates (12.9)
64.5
phytoplankton (150)
42.75
Unraveling a Fish Myth
• TE in Aquaculture [Avg. 40-60%]
• WHY?
– Nutritional profile of pelleted feeds
– Little energy expended hunting for food
– Bite-sized pellets size means little waste
– Also, no by-catch waste
– AQ feeds now 10-25% fish meal